SUBSTOICHIOMETRIC ISOTOPE-DILUTION ANALYSIS OF INDIUM BY LIQUID SCINTILLATION-COUNTING

A sensitive and selective substoichiometric isotope dilution method fo r the determination of trace amounts of indium is described. The metho d is based on the extraction of its ion-association complex with subst oichiometric amount of Aliquat-336 into toluene from 0.7 M KBr and 4.0 M H2SO4. The beta activity of indium-114 is measured by liquid scinti llation counting. The counting efficiency was found to be 92%. The eas e with which indium can be quantitatively collected over ferric hydrox ide is put to advantage in developing the above method. The collection method in conjunction with the substoichiometric method is used to de termine indium in the flue dust and zinc ore. The detection limit was found to be 0.5 mug in 100 ml of aqueous volume.